President Obama speaks in April after the Senate rejected a bill that would expand background checks on guns. The White House is seeking to clarify rules that bar firearm possession due to mental health problems.
Manuel Balce Ceneta/AP
hide caption

New York City Mayor Michael Bloomberg displays a confiscated AR-15 assault rifle in East Harlem as District Attorney Cy Vance (right) looks on during a news conference in October 2012 in New York City.
Mario Tama/Getty Images
hide caption

Former Rep. Gabby Giffords and her husband, Mark Kelly, at a gun show in Saratoga Springs, N.Y., in October. Giffords was shot in the head in a 2011 mass shooting in Tucson. She and Kelly have since founded a political action committee to push for tougher gun laws.
Tim Roske/AP
hide caption